Embodiments of the invention relate generally to a propulsion system and a method, and more particularly, relate to a propulsion system and a method for providing power to a vehicle by an energy-type energy source and a power-type energy source.
An energy-type energy source, such as battery, is usually employed to provide power to a traction drive system and capture regenerative energy in electric, and hybrid electric vehicles. However, the energy-type energy source cannot handle fast driving dynamics during motoring and regenerating. Hence, a power-type energy source, such as ultra-capacitor, may be a good complementary. Therefore, the energy-type energy source and the power-type energy source integrating with one or more DC-DC converters may be a suitable candidate to provide power for the vehicle. A required power for the traction drive system may be split between the energy-type energy source and the power-type energy source. Currently, the required power is split only according to state-of-charges of the energy-type energy source and the power-type energy source. However, the energy management strategy has low driving train efficiency.
It is desirable to provide a propulsion system and a method to address at least one of the above-mentioned problems.